Question

How is it that you can have both water and ice at $0^{\circ}C$ and both water and steam at $100^{\circ}C$?

Answer 1

Hint: We know that there exist different states of matter namely, the solids, liquids and gases. These are majorly due to the difference in the force of attraction or the bonding strength between the molecules. To break this we need energy.

Complete step-by-step answer:
We know that liquid water exists in different phases at different temperatures. For example, water exists as gas or steam in high temperature and the same water exists as solid ice in lower temperature.
We also know that temperature is the measure of transfer of heat energy. And we know that energy in the form of heat is required to change the phase of water. This energy is needed to overcome the force of attraction between the molecules, this happens without increasing the temperature, and is hence called latent heat coefficients.
At $0^{\circ}C$, there is just enough energy for the ice to melt into water. Thus both the phases exist, any rise in temperature results in water and similarly, and lower the temperature, results in the formation of ice.
At $100^{\circ}C$, there is just energy for the water to evaporate and become steam. Thus both the phases exist, any rise in temperature results in formation of steam and similarly, any fall or lower the temperature, results in the formation of water.

Note: The energy required to convert ice to water is called the latent heat of fusion and similarly, the energy required to convert water to steam or vapour is called the latent heat of vaporization. Here, the phases are in equilibrium and at constant temperature.